Notice that this time of year every damn fly on the planet gets into your house?
Worse, the damned things seem to have some kind of radar so that the moment you even think of a fly swater, they zoom off and hide!!!!!!!!!!!!!!!!!!!!!!!
It's like it's genetic; they know when you gone and got the thing to kill them so like the wind they are gone right up until the time you get out your chips and dip and then all of them are right there buzzing around like a gaggle of fighter planes!
I got some fly strips; plastic strips with sticky stuff on them so when the flies land on it they are stuck and the miserable little bastards starve to death.
Anyway, this is how it works in BFL Land as I am only a few miles from that hated facility.
My $.02.